Well, I'm not familiar with the "Q" series, but I'll tell you that I have an American Spector (NS-4). It's absolutely, hands down, the best bass I've ever encountered!

The workmanship is incredible, the versatility is tremendous, the feel is amazing, and the aesthetics are beautiful!

I've heard the Czech models are really nice too, but the Korean ones may not be as good...But, I've never played anything except the American ones, so my opinion of the other two models are not something I'd put any stock into. Perhaps other people can fill in those holes...